Since upgrading to version 2, I have been getting massive UI lag at various times. Sometimes I can edit a number of images with no appreciable lag, then suddenly it will cut in and the UI will become very unresponsive. This will normally survive a restart of darktable. The lag can start on first use, so the lag can survive reboots. When this happens I normally have to give up for the day.

The lag usually (as far as I can recall) occurs in the darktable section. It takes the form of 5-10+ second responses to the any UI action. It the action results in a hint pop-up, it can result in darktable hogging mouse input.

The lag is nothing to do with the image size as the previous version coped with these images okay, and as I say, it sometimes works no problem. There is no obvious CPU usage increase, beyond the usual, when this happens.

The issue appeared on my upgrade to v. 2.x (I forget the version). I tried the git version and am currently running: 2.1.0+179~gf46b8fc

Are you sure it's a "3" in the 2nd place? Because, darktable doesn't support that Lua version and shouldn't even compile. Please run ldd `which darktable` | grep lua to see what it's linked against.

Sorry, my mistake. I'm using Arch and messed up my package search (missed the wildcard). The installed package called Lua is 5.3, but there is also an installed 5.2 package (Lua52), and darktable is linked to that package (the version of Lua there, is 5.2.4).

ok, I have pushed a fix for the stable branch only. master will need a more complex fix

please report if you still see the problem when reenabling lua.

you will need to test with the stable branch, obviously...

Thank you for this.

The stable is darktable-2.0.x, yes?I've built with that branch, removing the -DUSE_LUA=Off in the cmake directives.

The first two times I ran the application from a shortcut key, it crashed when I double-clicked an image in Lightbox. I then ran it from the terminal and it didn't crash (no output). I ran it again from the short-cut key and again it didn't crash. I can keep this branch if you wish and monitor this.

Generally playing with the application - not got any images to properly work on at the moment - it seems to be as responsive as with Lua disabled. I should find time to play some more, but it looks very promising.